Structure and Dynamics of the VAULT COMPLEX

Vaults are the largest ribonucleoprotein particles found in eukaryotic cells. The maincomponent of these 13 MDa structures is the Mr 100,000 major vault protein (MVP).In mammalian cells, about 96 copies of this protein are necessary to form one vaultparticle. Two additional proteins are associated with the complex, the so-called minorvault proteins of Mr 193,000 (VPARP) and Mr 240,000 (TEP1), as well as severaluntranslated RNA molecules of 86-141 bases. The components are arranged into ahollow barrel-like structure with each half representing eight arches, which are reminiscent to the arched vaulted ceilings of cathedrals. Therefore, when vaults werefirst observed as contaminants in a preparation of clathrin coated vesicles form rat liver,the large complexes were named ‘vaults’. The typical morphology and the individualvault constituents appear conserved throughout evolution, implying an important rolefor vaults in cellular metabolism. A number of functions have been suggested for theseunique particles, but the general idea is that vaults function in intracellular transportprocesses. Nevertheless, the precise cellular function of the vault complex has not yetbeen elucidated. In this study we attempted to gain insight in vault biogenesis,dynamics and their interaction with other cellular components in order to unravel thephysiological significance of vaults